This invention relates in general to rail car construction and in particular to a new and useful universal coupling for rail car trucks.
A similar coupling is disclosed in German OS 23 53 256 (FIG. 2). In this prior art coupling, universal mobility is obtained by providing between the outer parts of the coupling two planar coupling zones, one after the other. Each coupling zone is formed by individual rubber stacks which are uniformly distributed over the circumference. The rubber stacks are mounted in positions to make a hub spider of the outer part interengaged in the individual joint planes with a spider having an equal number of arms and being provided on the respective end of the intermediate shaft. Gaps are thereby formed into which the individual rubber stacks are inserted in a prestressed state. Prestressing, position, and spring rate of the rubber stacks are brought into such relation that in an assembled state, the sum of all acting forces is zero. No residual circumferential force remains which could put the system out of balance. The dimensioning of this prior art double coupling not only depends on the properties of the individual stacks having to satisfy simultaneously requirements of torsional resilience and restoring force, but also the loadability of the spider arms. Due to the involved geometry, cast material of relatively high quality, such as cast steel, must be employed. This makes the coupling relatively heavy.